In the middle of the movie when Margo is on Logan's lap, and doing..you know what, and then David comes and hurts her....what EXACTLY is he doing to her? I can't tell what he's doing cause the camera doesn't show what he's doing. Does any1 know?

I was just watching the movie last night and noticed that he grabs her but she smiles at first and then he grabs her harder or something I don't know what he's doing. I always wonder when I watch the movie.